Indexing device



April 22, H2M. F. TURRETTIN:

INDEXING DEVICE Filed Feb. 3, 1940 Patented Apr. 22, 1941 INDEXING DEVICE Fernand Turrettni, Bellevue-Geneva, Switzerland, assignor to Societe .Genevoise dInstruments de Physique, Geneva, Switzerland, a firm of Switzerland application February 3, 1940, seri-a1 No. 317,208 In Switzerland February 23, 1939 (o1. err-5c) 5 Claims.

The present invention relates to a device for maintaining the rotatable table of a machine tool lin different vpredetermined positions.

The devices used in machine tools for this purpose are numerous and a high degree of vaccuracy is required thereof. Furthermore their handling must be a rapid one in order to diminish to a minimum the time wanted for the machining of the work pieces. For this reason preferably dividing devices defining a certain number of fixed angular positions are used and are known under the name of indexing devices. Generally they comprise a disc provided with holes or notches or else with abutments integral with the rotatable disc or table of the device. Indexing plates of kgreat dimensionsLas used on boring or milling machines, are usually provided on their lower face with the wanted number of abutting surfaces formed by blocks or axles of hardened steel. several bolts orwedges guided in the base of the device. The dividers of this kind permit to obtain a good precision, but unfortunately they are subjected torapid wear'o'naccount of the friction produced betweenfthe surfaces which determine the assumed position of the indexing plate, when locking the ybolts or wedges.l

The object of the present invention is to avoid the above cited inconveniences by providing an indexing device which will not be subjected to wear. According to the invention the device comprises, on the one hand, on the table, for each of said positions a roller freely rotatable around a pivot mounted in said table, and on the other hand, on the frame of the machine, two sliding members guided in this frame and adapted to be shifted in opposite directions over equal way lengths by means of a common operating organ and being destined to clamp between each other the roller broughtinto juxtaposition thereto. In this manner any friction between the roller and Y the sliding members is avoided and, consequently,

the wear as well of the surfaces determining the indexing position.

The accompanying drawing illustrates by way of example one embodiment of the present invention.

Figure 1 is a view of the embodiment in vertical, axial section.

Figure 2 shows a section along line Fig. 1.

Figure 3 shows a modification of a detail of the embodiment. n

In the Figures 1 and 2, the table I of the machine tool rotates in a central bearing 3 of the The abutments co-operate with one or machine frame 2. Thistable carries at its lower side a series` of pivots 4, Ii, 6, 'I .which dene predetermined angular positions vof the table.

Each pivot is xed in the table by means of two cones `8 `and 9 of opposite taper in such a manner that by tightening the screw nut I the pivot gets rigidly fastened in the sleeve II which itself is fixed in the table plate and shows conical seats f :for the cones 8 and 9. It will be useful to split theconical pieces 8, 9 .and I IL in order `togive them a certain elasticity sothat any play in the fixation can be suppressed by the single tightening of the screw nut IU.

The pivots 4, 5, 6, 'I carry each aroller I2, I3, I4, I5 respectively, whichrotates freely, however without play, a condition which is easily practicable if the pivot and the roller are both made of a very hard material, such as hardened f steel.

The roller `determining momentarily .the assumed position of the table r(see Fig. 2) isengaged between two sliding members I6 and I'I and is urged between their surfaces I8 and I9, the latter I9 of which is inclined with respect to the displacing direction of the sliding member I1. The

two sliding members are simultaneously and ,parallelly movable along a radius of the table and over equal length of way by means of a pinion 2l! rigidly mounted on a shaft 2| which can be operated by the handle 22. 29is an abutment of the sliding member I6. Any other mechanical device could be used, which actuates the two sliding members I6 and I'I oppositely to each other and imparts displacements of equal way length upon them.

It is apparent that the simultaneous and equal displacement of the two sliding members in opposite directions effects at the moment of the tightening a slight rotation of the roller I4 around its pivot 6, whereby any slipping and wear of the periphery of the roller is prevented, in spite of the only linear contact with and the high pressure exerted by the surfaces I8 and I9. Furthermore it is apparent that the bore of the roller, as well as the corresponding portion of the pivot are not worn, as the effort thereupon is weak and is distributed over a relatively large surface, which can easily be lubricated (for instance by means of the wick 23 being dipped into the oil bath 24).

The angle of inclination of the surface I9 is rather small in order that the clamping of the roller be irreversible.

Figure 2 shows the indexing device locked upon the roller I4. If the handle 22 is turned in anticlockwise direction, the sliding member I6 is shiftedto the left and the other one I`I to the right. This unlocking movement is limited by the abutment 29. The clamping surfaces IS and I9 of the two sliding members are of such size that in unlocking position the rollers I2, I3, I4, I can freely pass between the guides 25-25, and 21-28 without touching the sliding members, thus permitting the free rotation of the table I for bringing it into a new position. To lock the device again, it is suflicient to turn the handle 22' in clockwise direction, wherethrough the roller will be clamped between the surfaces I8 and I9.

For rendering the position of the divider independent from errors of manufacture of the index plate I, the pivots 4, 5, 6, 'I can be eccentrica] as shown in Figure 3, that is to say, the axis of the portion 39 around which the roller rotates is eccentric with respect to the body of the pivot so that the tangential position of the roller could be adjusted to a certain extent byk rotating the pivot; this will be sufficient to render, .for instance, the spacing of the rollers perfectly regular.

It is to be understood that the invention is not limited to that which is illustrated in the drawing; in particular could the space between succeeding rollers be unequal.

I claim:

1. Device for maintaining the rotatable table of a machine tool in different predetermined positions, having in combination a frame, a table mounted for rotation on said frame, a series of pivots on said table to deiine the determined angular positions thereof, for each of said pivots a roller mounted to freely rotate thereon, two sliding members guided in said frame and adapted to be shifted in opposite directions over equal way lengths, and a common operating member for actuating simultaneously both said members, each of the rollers being adapted to be brought into juxtaposition to the sliding members, and said members being destined to clamp said roller between each other.

2. Device for maintaining the rotatable table of a machine tool in different predetermined positions, having in combination a frame, a table mounted for rotation on said frame, a series of pivots on said table to dene the determined angular positions thereof, for each of said pivots a roller mounted to freely rotate thereon, two sliding members guided in said frame and adapted to be shifted in opposite directions over equal way lengths, a rack formed on each of said members, and a common operating pinion meshing with said racks for actuating simultaneously both said members, each of the rollers being adapted to be brought into juxtaposition to the sliding members, and sai-d members being destined to clamp said roller between each other.

3. Device for maintaining the rotatable table of a'machine tool in diiierent predetermined positions, having in combination a frame, a table mounted for rotation on said frame, a series of pivots on said table to deiine the determined angular positions thereof, means for fixing each pivot to said table, said means comprising two cones of opposite taper placed upon the pivot, a sleeve secured to the table and having tapered seats to engage said cones, said cones and sleeve being split so as to be elastic, and an axial tightening device acting upon said cones and adapted to suppress any play in the iixation, for each of said pivots a roller mounted to freely rotate thereon, two sliding members guided in said frame and adapted to be shifted in opposite di* rections over equal way lengths, and a common operating member for actuating simultaneously both said members, each of the rollers being adapted to be brought into juxtaposition to the sliding members, and said members being destined to clamp said roller between each other.

4. Device according to claim 3 in which the Ytwo sliding members are guided so as to move parallelly to each other along a radius of said rotatable table to contact with the juxtaposed roller, the V contact surface `of one of said members being parallel to the direction of displacement and the contact surface of the other of said members being inclined to said direction so as to act as a wedge for clamping said roller.

5. Device according to claim 3 in `which pivots carrying the rollers are eccentric with a View to adjusting the positions of said rollers one to another.

FERNAND TURRET'I'INI. 

